Radiation-curable vinyl paint containing pendant unsaturation with intervening ether functionality

ABSTRACT

A FILM-FORMING, RADIATION-POLYMERIZABLE, PAINT BINDER SOLUTION OF VINYL MOMOMERS AND AN OLEFINICALLY UNSATURATED VINYL MONOMER-COMPRISING POLYMERIC BINDER IS APPLIED AS A LIQUID COATING TO AN EXTERNAL SURFACE OF AN ARTICLE OF MANUFACTURE AND CURED THEREON WITH IONIZING RADIATION. THE BINDER POLYMER IS CHARACTERIZED BY HAVING OLEFINIC UNSATURATION BETWEEN THE TERMINAL CARBONS OF THE SIDE CHAINS, I.E., ALPHA-BETA UNSATURATION WITH SAID UNSATURATION BEING SEPARATED FROM THE PRINCIPAL CARBON-TOCARBON CHAIN BY TWO ETHER LINKAGES. THE BINDER POLYMER IS FORMED BY REACTING AN ALLYLIC ALCOHOL WITH A POLYMER FORMED BY REACTING AN UNSATURATED GLYCIDYL ETHER WITH AT LEAST TWO DIFFERENT VINLY MONOMERS AT LEAST ONE OF WHICH IS AN ESTER OF ACRYLIC OR METHACRYLIC ACID.

United States Patent 3,642,939 RADIATION-CURABLE VINYL PAINT CONTAIN-ING PENDANT UNSATURATION WITH INTER- VENING ETHER FUNCTIONALITY John F.Fellers and James E. Hinsch, Livonia, and Ernest O. McLaughlin, GardenCity, Mich., assignors to Ford Motor Company, Dearborn, Mich. NoDrawing. Filed Nov. 4, 1968, Ser. No. 773,346 Int. Cl. C08g 45/04 US.Cl. 260-836 15 Claims ABSTRACT OF THE DISCLOSURE A film-forming,radiation-polymerizable, paint binder solution of vinyl momomers and anolefinically unsaturated vinyl monomer-comprising polymeric binder isapplied as a liquid coating to an external surface of an article ofmanufacture and cured thereon with ionizing radiation. The binderpolymer is characterized by having olefinic unsaturation between theterminal carbons of the side chains, i.e. alpha-beta unsaturation, withsaid unsaturation being separated from the principal carbon-tocarbonchain by two ether linkages. The binder polymer is formed by reacting anallylic alcohol with a polymer formed by reacting an unsaturatedglycidyl ether with at least two dilferent vinyl monomers at least oneof which is an ester of acrylic or methacrylic acid.

This invention relates to the art of coating and is concerned with paintand articles of manufacture, particularly articles having externalsurfaces of wood, metal or polymeric solid coated with an adherentcoating of a film-forming, radiation-polymerizable, paint binder solution of vinyl monomers and an alpha-beta olefinically unsaturated vinylmonomer-comprising binder polymer having alpha-beta olefinicallyunsaturated side chains characterized in that such unsaturation isseparated from the principal carbon-to-carbon chain by two etherlinkages, i.e.

Heretofore, side chain unsaturation in radiation-polymerizable paintshas been separated from the principal carbon-to-carbon chain of thebinder polymer by one or more ester linkages. Films cast by thesepolymers are more resistant to hydrolysis than films cast from polymershaving ester linkages and hence the paints of this invention providesuperior corrosion protection and weather'ability.

In this application, the term paint is meant to include pigment and/orfinely ground filler in the binder solution, the binder solution withoutpigment and/ or filler or having very little of the same, 'which can betinted if desired, and other surface coating compositions containing thebinder solution which might be considered to be broadly analogous toenamel, varnish, or lacquer bases. Thus, the binder solution, which isultimately converted to a durable film resistant to weathering, can beall or virtually all that is used to form the film, or it can be avehicle for pigment and/or particulate filler material.

The term ionizing radiation as employed herein means radiation havingsufiicient energy to efifect polymerization of the paint films hereindisclosed, i.e., energy equivalent to that of about 5,000 electron voltsor greater. The preferred method of curing films of the instant paintsupon substrates to which they have been applied is by subjecting suchfilms to a beam of polymerization elfecting electrons having an averageenergy in the range of about 100,000 to about 500,000 electron volts.When using such a beam, it is preferred to employ a minimum of 25,000

3,642,939 Patented Feb. 15, 1972 volts per inch of distance between theradiation emitter and the workpiece where the intervening space isoccupied by air. Adjustment can be made for the relative resistance ofthe intervening gas which is preferably an oxygen-free inert gas such asnitrogen or helium. We prefer to employ an electron beam which at itssource has average energy in the range of about 150,000 to about 450,000electron volts.

The films formed from the preferred embodiments of the paints of thisinvention are advantageously cured at relatively low temperatures, e.g.between room temperature (20 to 25 C.) and the temperature at whichsignificant vaporization of its most volatile components is initiated,ordinarily between 20 and 70 C. The radiation energy is applied at doserates of about 0.1 to about 100 mrad per second upon a preferably movingworkpiece with the coating receiving a total dose in the range of about0.5 to about 100, ordinarily between about 1 and about 25, and mostcommonly between about 5 and about 15 mrad.

The polmeric paint binders of this invention have an average molecularweight above about 500, advantageously between about 1,000 and about50,000, and preferably about 4,000 to about 20,000. They contain about0.5 to about 5, advantageously about 0.5 to about 3.5, and preferablyabout 1 to about 3, units of alpha-beta olefinic unsaturation per 1,000units molecular weight. The term alpha-beta olefinic unsaturation asused herein means olefinic unsaturation between the two terminal carbonsof polymer side chains.

The vinyl monomer-comprising copolymer which is subsequently reactedwith an allylic alcohol to form the binder polymer is itself formed byreacting an unsaturated glycidyl ether with two or more different vinylmonomers.

The term vinyl monomer as used herein refers to a monomeric compoundhaving a ice terminal group and excludes allylic compounds. The preferred vinyl monomers are esters of C -C monohydric alcohols and acrylicor methacrylic acid, e.g. methyl methacrylate, ethyl acrylate, butylacrylate, butyl methacrylate, octyl acrylate, Z-ethyl hexyl acrylate,etc. Alcohols of higher carbon number, e.g. C C can also be used toprepare such esters. To simplify description the esters of acrylic acidand methacrylic acid are hereinafter termed acrylates. Vinyl hydrocarbonmonomers, e.g. styrene and alkylated styrenes such as vinyl toluene,alpha-methyl styrene, etc., may be used separately or in combinationwith the aforementioned acrylates. In combination with the acrylatemonomers and/or vinyl hydrocarbon monomers, there may be used minoramounts of other vinyl monomers such as nitriles, e.g. acrylonitrile,acrylamide, or N-methylol acrylonitrile, vinyl halides, e.g. vinylchloride, and vinyl carboxylates, e.g. vinyl acetate. The paint bindersolutions contain about 15 to about 75, preferably about 20 to about 60,weight percent, vinyl monomers. In a preferred embodiment, the vinylmonomers and the binder polymer of this invention together comprise atleast about weight percent of said binder. Minor amounts of otherpolymerizable monomers, e.g. allylic compounds, may be used to make upthe balance, if any.

This invention is particularly concerned with those coatings wherein thefilm-forming solution consists esinvention, herein defined to meancoatings wherein the 3 sum of these two components constitute at leastabout 85 weight percent of the film-forming binder.

The allylic alcohol used to impart the alpha-beta olefinic unsaturationto the binder polymer is ordinarily a C to C allylic alcohol, e.g. allylalcohol, 2-methyl-2-propen- 1-01, cinnamyl alcohol(3-phenyl-2-propen-1-ol), 2- phenyl-Z-propen-l-ol, etc. Theaforementioned alcohols may have alkyl substitution with resultantincrease in the number of carbon atoms per molecule to as high as about14.

The unsaturated glycidyl ethers used in the preparation of the aforesaidcopolymer are ordinarily a C to C glycidyl ethers but will contain 17carbon atoms where the ether is formed from a C alcohol andepichlorohydrin and include such compounds as allyl glycidyl ether,l-butene glycidyl ether and glycidyl ethers formed from theaforementioned allylic alcohols. Such ethers can be prepared by the wellknown reaction of such alcohols and epichlorohydrin or by the WilliamsonSynthesis.

The paint film may be applied by any conventional technique such asspraying, roll coating, dip coating, flow coating, etc. The film isconventionally applied to an average depth in the range of about 0.1 toabout 4 mils.

The invention will be more fully understood from the followingillustrative examples:

EXAMPLE 1 A vinyl monomer-comprising polymer is prepared from thefollowing reactants:

Parts by weight Ethyl acrylate 38.8 Methyl methacrylate 23.2 Allylglycidyl ether 37.0 Benzoyl peroxide 1.0 Xylene (solvent).

To a reaction vessel provided with a condenser, thermometer, agitator,and dropping funnel there are charged an amount of xylene equal inweight to the reactants to be added in the first reaction step. Thexylene is heated to about 100l20 C. The four reactants are thoroughlymixed and added slowly with a dropping funnel to the heated xylene overa period of four hours. The reaction is held at this temperature for l2hours after addition is complete and then allowed to cool to roomtemperature.

A binder polymer is formed in a second reaction step from the followingmaterials:

Parts by weight Copolymer from Step I 69.4 Allyl alcohol 30.4 Potassiumhydroxide 0.2

A solution of the allyl alcohol and potassium hydroxide is added to thecopolymer at room temperature. The mixture is then heated to atemperature of 100-120 C. This temperature is maintained for about 7hours and allowed to cool. The binder polymer reaction mixture is heatedto about 60 C. and the xylene and excess reactant are removed by vacuumdistillation.

At a temperature of about 60 C. styrene and hydroquinone are added tothe polymer to form a film-forming solution having the followingcomposition:

Parts by weight Polymer from Step II 66.66 Styrene 33.27 Hydroquinone0.07

The film-forming solution is applied to a metal substrate to an averagedepth of about 0.3 mil and cured thereon by electron beam irradiation.The conditions of irradiation are as follows:

Voltage: 270 kv. Current: 25 milliamperes Total dosage: 15 mradsAtmosphere: Nitrogen 4 EXAMPLE 2 The procedure of Example 1 is repeatedwith the single difference that an equivalent amount of methylmethacrylate is substituted for the styrene monomers in the filmformingsolution.

EXAMPLE 3 The procedure of Example 1 is repeated with the singledifference that an equivalent amount of a mixture of styrene, ethylacrylate and 2-ethyl hexyl acrylate is substituted for the styrenemonomers in the film-forming solution.

EXAMPLE 4 The procedure of Example 1 is repeated except that anequimolar mixture of methyl methacrylate and vinyl toluene issubstituted for the styrene monomers in the filmforming solution, thesubstrate is wood, and the film depth is about 1 mil.

EXAMPLE 5 The procedure of Example 1 is repeated except that thefilm-forming solution contains about 30 wt. percent of the polymericbinder and about wt. percent of a mixture of styrene and butylmethacrylate.

EXAMPLE 6 The procedure of Example 1 is repeated except that thefilm-forming solution contains about 70 wt. percent of the polymericbinder and about 30 wt. percent of a mixture of alpha-methyl styrene,ethyl acrylate, and butyl acrylate.

EXAMPLE 7 The procedure of Example 1 is repeated with the folr lowingchanges:

(a) The reactants of the first step reaction are:

Parts by weight Butyl acrylate 38.8 Styrene 23.2 Allyl glycidyl ether37.0

Benzoyl peroxide 1.0

(b) The reactants of the second step reaction are:

Parts by weight Copolymer from (a) 69.4 l-penten-S-ol 30.4 Potassiumhydroxide 0.2

(c) Composition of film-forming solution:

Parts by weight Polymer from (b) 66.6 Methylmethacrylate 33.27Hydroquinone 0.07

EXAMPLE 8 EXAMPLE 9 The procedure of Example 7 is repeated except thatan equivalent amount of cinnamyl glycidyl ether is substituted for theallyl glycidyl ether component of the first step reaction, 9-decen-l-olis substituted for the lpenten-S-ol of the second reaction step and thevinyl monomers of the binder solution are equimolar mixture of styreneand methyl methacrylate.

EXAMPLE 10 The procedure of Example 7 is repeated with the differencesthat the constituent monomers of the first step reaction and the amountof allylic alcohol in the second step reaction are adjusted to provide apolymeric binder containing about 0.7 alpha-beta olefinic unsaturationunits per 1,000 units molecular weight and the vinyl monomers of thebinder solution are an equimolar mixture of styrene and methylmethacrylate.

EXAMPLE 11 The procedure of Example 7 is repeated with the differencesthat the constituent monomers of the first step reaction and the amountof allylic alcohol in the second step reaction are adjusted to provide apolymeric binder containing about 4.5 alpha-beta olefinic unsaturationunits per 1,000 units molecular weight and the vinyl monomers of thebinder solution are an equimolar mixture of styrene and methylmethacrylate.

EXAMPLE 12 The procedure of Example 7 is repeated with the differencesthat the constituent monomers of the first step reaction and the amountof allylic alcohol in the second step reaction are adjusted to provide apolymeric binder containing about 1 alpha-beta olefinic unsaturationunits per 1,000 units molecular weight and the vinyl monomers of thebinder solution are an equimolar mixture of styrene and methylmethacrylate.

EXAMPLE 13 The procedure of Example 7 is repeated with the differencesthat the constituent monomers of the first step reaction and the amountof allylic alcohol in the second step reaction are adjusted to provide apolymeric binder containing about 3 alpha-beta olefinic unsaturationunits per 1,000 units molecular Weight and the vinyl monomers of thebinder solution are an equimolar mixture of styrene and methylmethacrylate.

EXAMPLE 14 The procedure of Example 1 is repeated with the followingchanges:

-(a) The reactants of the first step reaction are:

Parts by weight Ethyl acrylate 38.8 Methyl methacrylate 23.2 l-buteneglycidyl ether 37.0 Benzoyl peroxide 1.0

-(b) The reactants of the second step reaction are: Parts by weightCopolynier from (a) 69.4 Allyl alcohol 30.4 Potassium hydroxide 0.2

(c) Composition of film-forming solution Parts by weight Polymer from(a) 67.2 Methyl methacrylate 32.4 Hydroquinone 0.07

The term copolymer as used herein means a polymer of two or more vinylmonomers and an unsaturated glycidyl ether.

The abbreviation mrad" as employed herein means 1,000,000 rad. The termrad as employed herein means that dose of radiation which results in theabsorption of 100 ergs of energy per gram of absorber, e.-g. coatingfilm. The electron emitting means may be a linear electron acceleratorcapable of producing a direct current potential in the rangehereinbefore set forth. In such a device electrons are ordinarilyemitted from a hot filament and accelerated through a uniform voltagegradient. The electron beam, which may be about A; inch in diameter atthis point, is then scanned to produce a fan-shaped beam and then passedthrough a metal window, e.g. a magnesium-thorium alloy, aluminum, analloy of aluminum and a minor amount of copper, etc., of about 0.003inch thickness.

The filmiorming material should have a viscosity low enough to permitrapid application to the substrate in substantially even depth and highenough so that a 1 mil (.001 inch) film will hold upon a verticalsurface without sagging. The viscosity of the binder can be adjusted byvarying the relative concentrations of the resin component and/or byvarying the relative concentrations of dissimilar monomers within themonomer component. The binder is preferably applied to the substrateessentially free of nonpolymerizable organic solvents and/or diluents.

The number of alpha-beta olefinic unsaturation units in the binder resinper 1,000 units molecular weight is most accurately determined by actualmeasurement by conventional testing after a sample of the resin has beenprepared.

It will be understood by those skilled in the a1t that modifications canbe made within the foregoing examples within the scope of the inventionas hereinbefore described and hereinafter claimed.

What is claimed is:

1. An article of manufacture comprising a substrate and an adherentcoating of paint on an external surface thereof, said coating of painton a pigment and particulate filler-free basis comprising the in situformed polymerization product of a film-forming dispersion consistingessentally of (a) about 15 to about weight percent vinyl monomersconsisting essentially of vinyl monomers selected from the groupconsisting of alkyl esters of acrylic or methacrylic acid and 'vinylhydrocarbon monomers and (b) about to about 25 weight percent of a vinylmonomer-comprising binder polymer having side chain, alpha-beta,olefinic unsaturation each unit of which is separated from the principalcarbon-to-carbon chain by two ether linkages, said binder polymer beingformed by reacting a C to C allylic alcohol with a polymer consistingessentially of the polymerization product of a C to C unsaturatedglycidyl ether with at least two different vinyl monomers selected fromthe group consisting of alkyl esters of acrylic or methacrylic acid andvinyl hydrocarbon monomers, said binder polymer being furthercharacterized in that the alpha-beta olefinic unsaturation therein islimited to a concentration in the range of about 0.5 0 about 5 units per1,000 units molecular weight, crosslinked on said surface by ionizingradiation.

2. An article of manufacture comprising a substrate and an adherentcoating of paint on an external surface thereof, said coating of painton a pigment and particulate filler-free basis comprising the in situformed polymerization product of a film-forming dispersion consistingessentially of (a) about 15 to about 75 weight percent vinyl monomersconsisting essentially of vinyl monomers selected from the groupconsisting of esters of acrylic or methacrylic acid and a C -Cmonohydric alcohol and C -C monovinyl hydrocarbons and (b) about 85 toabout 25 weight percent of a vinyl monomer-comprising binder polymerhaving side chain, alpha-beta, olefinic unsaturation each unit of whichis separated from the principal carbon-to-carbon chain by two etherlinkages, said binder polymer being formed by reacting a C to C allylicalcohol with a polymer consisting essentially of the polymerizationproduct of a C to C unsaturated glycidyl ether with at least twodifferent vinyl monomers selected from the group consisting of esters ofacrylic or methacrylic acid and a C C monohydric alcohol and C -Cmonovinyl hydrocarbons, said binder polymer being further characterizedin that the alpha-beta olefinic unsaturation therein is limited to aconcentration in the range of about 0.5 to about 5 units per 1,000 unitsmolecular weight, crosslinked on said surface by ionizing radiation.

3. An article of manufacture in accordance with claim 2 wherein saidallylic alcohol is a C to C allylic alcohol.

4. An article of manufacture in accordance with claim 2 wherein saidunsaturated glycidyl ether is a C -C allylic glycidyl ether.

5. An article of manufacture in accordance with claim 2 wherein saidalpha-beta olefinic unsaturation in said binder polymer is limited to aconcentration in the range of about 0.5 to about 3.5 units per 1,000units molecular weight.

6. An article of manufacture in accordance with claim 2 wherein saidalpha-beta olefinic unsaturation in said binder polymer is limited to aconcentration in the range of about 1 to about 3 units per 1,000 unitsmolecular weight.

7. An article of manufacture in accordance with claim 2 wherein thevinyl monomers in said film-forming dispersion are a mixture of vinylhydrocarbon monomers and an alkyl ester of acrylic or methacrylic acid.

8. An article of manufacture in accordance with claim 2 wherein saidfilm-forming dispersion on a pigment and particulate filler-free basisconsists essentially of about 20 to about 60 weight percent vinylmonomers and about 80 to about 40 weight percent of said binder polymer.

9. A radiation-curable paint which on a pigment and particulatefiller-free basis consists essentially of a filmforming dispersionconsisting essentially of (a) about 15 to about 75 weight percent vinylmonomers consisting essentially of vinyl monomers selected from thegroup consisting of alkyl esters of acrylic or methacrylic acid andvinyl hydrocarbon monomers and (b) about 85 to about 25 weight percentof a vinyl monomer-comprising binder polymer having side chain,alpha-beta, olefinic unsaturation each unit of which is separated fromthe principal carbon-to-carbon chain by two ether linkages, said binderpolymer being formed by reacting a C to C allylic alcohol with a polymerconsisting essentially of the polymerization product of a C to Cunsaturated glycidyl ether with at least two different vinyl monomersselected from the group consisting of alkyl esters of acrylic ormethacrylic acid and vinyl hydrocarbon monomers, said binder polymerbeing further characterized in that the alpha-beta olefinic unsaturationtherein is limited to a concentration in the range of about 0.5 to about3.5 units per 1,000 units molecular weight.

10. A radiation-curable paint which on a pigment and particulatefiller-free basis consists essentially of a filmforming dispersionconsisting essentially of (a) about 15 to about 75 weight percent vinylmonomers consisting essentially of vinyl monomers selected from thegroup consisting of esters of acrylic or methacrylic acid and a C -Cmonohydric alcohol and C C monovinyl hydrocarbons, and (b) about 85 toabout 25 weight percent of a vinyl monomer-comprising binder polymerhaving side chain, alpha-beta, olefinic unsaturation each unit of whichis separated from the principal carbon-to-carbon chain by two etherlinkages, said binder polymer being formed by reacting a C to C allylicalcohol with a polymer consisting essentially of the polymerizationproduct of a C to C unsaturated glycidyl ether with at least twodifferent vinyl monomers selected from the group consisting of esters ofacrylic or methacrylic acid and a C -C monohydric alcohol and C -Cmonovinyl hydrocarbons, said binder polymer being further characterizedin that the alpha-beta olefinic unsaturation therein is limited to aconcentration in the range of about 0.5 to about 3.5 units per 1,000units molecular weight.

11. A radiation-curable paint in accordance with claim 10 wherein saidallylic alcohol is a C to C alylic alcohol.

12. A radiation-curable paint in accordance with claim 10 wherein saidunsaturated glycidyl ether is a C C allylic glycidyl ether.

13. A radiation-curable paint in accordance with claim 10 wherein saidalpha-beta olefinic unsaturation in said binder polymer is limited to aconcentration in the range of about 1 to about 3 units per 1,000 unitsmolecular weight.

14. A radiation-curable paint in accordance with claim 10 wherein thevinyl monomers in said film-forming dispersion are a mixture of vinylhydrocarbon monomers and an alkyl ester of acrylic or methacrylic acid.

15. A radiation-curable paint in accordance with claim 10 wherein saidfilm-forming dispersion on a pigment and particulate filler-free basisconsists essentially of about 20 to about weight percent vinyl monomersand about to about 40 weight percent of said binder polymer.

References Cited UNITED STATES PATENTS 3,317,635 5/ 1967 Osmond 260-8363,397,166 8/1968 Schmidle 260885 3,390,206 6/1968 Thompson 2608853,514,500 5/1970 Osmond 260-885 PAUL LIEBERMAN, Primary Examiner US. Cl.X.R.

